The COVID-19 pandemic made it harder to communicate accurate information about vaccines because of the spread of misinformation. The European Medicines Agency (EMA) tried to reas-sure the public by communicating about the development and approval of COVID-19 vaccines. They surveyed patients/consumers, healthcare professional organizations, and individual stake-holders to see if their core information materials were informative and well understood. They also asked about the public's preferred communication channels. The surveys showed that indi-vidual patients/consumers generally prefer to get information about COVID-19 vaccines from the internet or mass media. Organizations and individual healthcare professionals prefer to get in-formation from national and international health authorities' sources. This supports EMA's ap-proach of using media, stakeholder engagement, and web-based formats to communicate about COVID-19 vaccines. Both at the EU and local levels, participants had a good understanding of the key messages from regulators and found the materials useful and relevant. However, some im-provements were recommended to the visuals, texts, and dissemination formats. These recom-mendations were generally consistent in both contexts. User-testing of proactive communication materials aimed at prebunking misinformation during a public health crisis helps to ensure that users understand the development and safety safeguards of novel vaccine technologies. This in-formation can then be used as a basis for evidence-based communication activities by regulators and public health bodies in an emergency context.